[PostgreSQL] Значение, возращаемое функцией

CREATE OR REPLACE FUNCTION getSensorValues(firstTime integer, lastTime integer, step integer, insensorid integer)
returns setof getSensorType as --table(otime_t integer, ovalue float8) as
$$
declare
firstTime integer := $1;
counter integer := 0;
localStep integer := $3/10 + 1;
getSens getSensorType;
occ record;
begin
  while firstTime < $2 + 1 
  loop
  for occ in select time_t, value from sensors
  where sensorsid = $4 and time_t = (select min(time_t) from sensors
  where sensorsid = $4 and time_t >= (firstTime - (localStep/2) + (localStep*counter))
  and time_t < (firstTime + (localStep/2) + (localStep*counter)))
  loop
  getSens.otime_t := occ.time_t;
  getSens.ovalue := occ.value;
  return next getSens;
  end loop;
  firstTime := firstTime + $3;

  if (getSens.otime_t is NULL) then
    if (getSens.ovalue is NULL) then
      if (counter < 9) then
    firstTime := firstTime - $3;
    counter := counter + 1;
      end if;
    end if;
  end if;

  end loop;
return;
end;
$$
language 'plpgsql';

------------------------------------------------

create type getSensorType as
(
otime_t integer,
ovalue float8
);